Leucovorin is one of several active, chemically reduced derivatives
of folic acid. It is useful as an antidote
to drugs which act as folic
acid antagonists. Also known as folinic acid,
Citrovorum factor, or 5­formyl­5,6,7,8­tetrahydrofolic
acid, this compound
has the chemical designation
of L­Glutamic acid, N­[4­[[(2­amino-5-formyl­1,4,5,6,7,8­hexahydro­4­oxo­6-pteridinyl)methyl]amino]benzoyl]­,calcium
salt (1:1). The formula
weight of leucovorin
calcium is 511.51.